1. Field of the Invention
This invention relates to electrographic development processes and, more particularly, to a support which maintains a receptor in a proper spaced relationship to a development roller.
2. Description of the Prior Art
An existing electrographic recording process described in detail in U.S. Pat. No. 3,909,258 issued to Kotz and incorporated herein by reference, utilizes a magnetic roller to transport magnetically attractable, relatively electrically conductive toner material around the surface of a development roller and into contact with a receptor which may be zinc oxide coated copy paper. The receptor is provided in an image area with an electrical charge which attracts toner material from the magnetic field and retains the toner particles in such area until they are subsequently affixed to the paper. A surplus of toner material is provided to the copy paper to ensure that all imaged areas are covered. This surplus of toner gradually builds up in a pool, wedge shaped in cross-section, at the interface of the toner and the copy paper.
This accumulation of surplus toner ordinarily causes no problem when a copy of conventional length (up to 14 inches) is produced because the accumulation of surplus toner is very small and is easily spread uniformly by continued movement of the toner and a doctor blade associated with the development roller.
Recently, however, modifications to the copy machine employing the development roller have enabled the production of copies in excess of 100 feet. When copies of such a length were produced, the surplus toner accumulated to such an extent in the conventional development structure that the accumulation could not pass between the development roller and the copy paper which is supported on a guide, called a "gapper", spaced a predetermined distance from the roller. This accumulation of toner remained at the interface of the gapper and the roller even after the copy paper had passed and would not allow subsequent sheets of the copy paper to pass between the development roller and the gapper. The accumulation may also result in contamination of the interior of the copy machine.
The surplus toner may be gradually dissipated by continued rotation of the development roller, but a large number of rotations may be required before a subsequent copy can be produced.
It is, therefore, desirable to provide the copy machine with a support or gapper which will not only properly position the copy paper with respect to the development roller, but also permit the passage of accumulated surplus toner so that such toner may be removed or spread uniformly around the roller.